9/10) Muscle Tissue Structure, Function & Disease Flashcards Preview

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Flashcards in 9/10) Muscle Tissue Structure, Function & Disease Deck (66)
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1
Q

Define myalgia

A

muscle pain

2
Q

Define myasthenia

A

muscle weakness

3
Q

Define myopathy

A

diseases of the muscle

4
Q

Define myocardium

A

muscle component of the heart

5
Q

Define myoclonus

A

sudden muscle spasm

6
Q

What are the different muscle types?

A

Striated - skeletal muscle, cardiac muscle

Non-striated - smooth muscle

7
Q

What is the function of myoglobin?

A

Store O2 and provide it to striated muscle

8
Q

What is a sarcolemma?

A

the outer membrane of the muscle

9
Q

What is sarcoplasm?

A

cytoplasm in muscle cells

10
Q

What is the sarcoplasmic reticulum?

A

Smooth endoplasmic reticulum in the muscle

11
Q

What is the sarcosome?

A

mitochondria in the muscle

12
Q

What is the sarcomere?

A

the STRIATED muscle contration unit

13
Q

What is the structure of skeletal muscle?

A

Epimysium - dense connective tissue surrounding the whole muscle
Perimysium - dense connecting tissue surrounding the fasicle
Endomysium - loose connective tissue surrounding the individual muscle fibres

14
Q

Where is the point of origin?

A

the muscle attachment site that does NOT move during muscle contraction

15
Q

Where is the point of insertion?

A

the muscle attachment site the DOES move during muscle contraction

16
Q

What is the function of skeletal muscle?

A

contraction in the direction of the muscle fibres

17
Q

What are extrinsic muscles?

A

muscle connected to BONE via tendons or cartilage

18
Q

What are intrinsic muscles?

A

muscles connected to other muscles

19
Q

Where are the nuclei located in skeletal muscle?

A

peripheral nuclei

20
Q

Describe the capillary netweork in skeletal muscle

A

Capillaries run parallel to the muscle then break through into the muscle fibre
thicker fiber = thicker capillary = more blood

21
Q

Describe the structure of myofibrils

A

Z bands - determine the size of the sarcomere
I band - only actin filament
A band - contains myosin filament (and actin)
H band - contains myosin ONLY
M line - centre of sarcomere

22
Q

What colour does myosin appear?

A

Dark

23
Q

What colour does actin appear?

A

light

24
Q

What happens to the sarcomere during contraction?

A

Z and I bands mover closer together as the actin slides over the myosin

25
Q

What are the 2 types of skeletal muscle fibres?

A

Slow twitch

Fast twitch

26
Q

State 8 characteristics of slow twitch fibres

A
Red colour
Carry out aerobic respiration
Many cytochromes
Many mitochondria
Rich capillary network
High mnyoglobin levels
Long distant exercise/fatigue resistant
Involves fatty acids
27
Q

State 8 characteristics of fast twitch muscle fibre

A
White in colour
anaerobic respiration
few cytochromes
few mitochondria
poor capillary network
few myoglobin
uses glycogen
sprinting/rapdly fatigue
28
Q

What 2 factors allow muscle contration to occur?

A

Ca2+ ions

ATP

29
Q

What is the role of titin in muscle contraction?

A

Titin pulls the actin back to its original position once muscle contraction has occured

30
Q

What is the contraction unit in cardiac muscle?

A

Cardiomyocytes

31
Q

What is hypertrophy?

A

the enlargement of cardiomyocytes

32
Q

What is atrophy?

A

the shrinking of cardiomyocytes

33
Q

What is hyper plasia?

A

The multiplication of cardiomyocytes

34
Q

Where are the nuclei in cardiac muscle fibres located?

A

Centrally suurounded by glycogen (white)

35
Q

How do impulses travel through the heart?

A

1) AP generated in the sinoatrial node
2) AP travels through the wall of the atria
3) AP reaches the atrioventricular node , causing a delay in the AP to allow the atria to contract
4) AP travels down the bundle branches to the purkinje fibres
5) AP travels to the walls of the ventricals to allow the heart to contract in unison

36
Q

What are purkinje fibres?

A

modified cardiomyocytes that conduct APs rapidly allowing the ventrical walls to contract in sync

37
Q

Give 3 characteristics of purkinje fibres

A

abundant glucose - good conductor of electricity
sparse myofibrils - function quickly
extensive gap junctions - function quickly

38
Q

What shape is smooth muscle?

A

fusiform (spindle shaped)

39
Q

Where are the smooth muscle nuclei located?

A

1 centrally located nuclei

40
Q

Why do smooth muscle tear less easily than other muscle?

A

It undergoes hypertrophy after hyperplasia

41
Q

What are the 3 types of tears?

A

mild
moderate
severe

42
Q

How do skeletal muscles repair muscle damage?

A

Satellite cells fuse with existing muscle mass to increase their muscle mass (hypertrophy)
Hyperplasia caused by satellite cells dividing

43
Q

How does cardiac muscle repaitrmuscle damage?

A

It cant

Fibroblasts invade damaged cells, divide and lay down scar tissue

44
Q

How does smooth muscle repair muscle damage?

A

Hyperplasia

45
Q

How can nerves cells impact skeletal muscle contration?

A

Varicosities!
contain vesicles and mitcohondria. Mitochondria activated and releases Ca2+ which causes the vescile to fuse withthe membrane and release its neurotransmitter

46
Q

How does the body slow down your heart rate?

A

Parasympathetic NS

Signal sent from the cranium through the vegas nerve to the atria. 2 nerves, 1 to each atrium

47
Q

How does your heart rate increase?

A

Sympathetic NS
Signal sent from spinal cord through sympathetic fibres to the ventricals, causing heart to beat faster.
Sends a nerve close to a cardiomyocyte which releases a neurotransmitter which acts on the sarcolemma of the cell membrane, inducing an electrical signal which acts on the t tubules which interacts with a calcium channel filled with DHP, causes shape change, then shape cahnge in adjacent protein. Allows Ca2+ out of SR into the cytoplasm where it interacts with actin by binding to troponin C, allowing contraction to occur

48
Q

Describe the events leading to skeletal muscle contraction?

A

1) Nerve impulse travels along the motor neurone to the neuromuscular junction
2) This activates vesicles causing them to fuse with the cell membrane, releasing acetylcholine into the synaptic cleft and depolarise the sarcolemma
3) The Ach bind to nicotinic acetylcholine receptors
4) This opens voltage gates Na+ channels to open, causing an influx of Na+
5) This causes general depolarisation over the sarcolemma and into t tubules
6) T tubule changes its confirmation
7) gated Ca2+ channels are opened and Ca2+ is released into the sarcoplasm
8) Ca2+ binds to troponin C, beginning contraction cycle
9) Ca2+ ions are returned to the terminal cisternae of the SR by SERCA

49
Q

What is myasthenia gravis?

A

An autoimmune disease caused by auto-antibodies binding to nicotinic Ach receptors and blocking them

50
Q

What symptoms are associated with myasthenia gravis?

A

Ptosis - droopy eye

Larger end plate terminal

51
Q

What makes up the troponon complex?

A

Troponin I
Troponin C - binds calcium
Troponon T

52
Q

How does a powerstroke occur?

A

1) ATP binds to myosin head, (conf change)brings it closer to actin
2) ATP hydrolysis occurs, ADP + Pi formed (stays attached to myosin head), brings myosin head even closer to actin (conf change)
3) Myosin head binds to actin
4) ADP + Pi unbind from myosin (conf change), pulls actin towards M line

53
Q

What is an agonist?

A

The prime mover (main muscle responsible for a movement)

54
Q

What is an antagonist?

A

Oppose agonist

55
Q

What is a synergist?

A

Assist agonists

56
Q

What is a neutraliser?

A

prevent the unwanted actions that an agonist can perform

57
Q

What are fixators?

A

Act to hold a body part immobile whilst another body part is moving

58
Q

What causes compartment syndrome?

A

Trauma in one compartment could cause internal bleeding which exerts pressure on blood vessels and nerves

59
Q

State 3 symptoms of compartment syndrome

A
  • deep constant poorly localised pain
  • bruising and swelling
  • parasthesia (pins and needles)
60
Q

How is compartment syndrome treated?

A

Fasciotomy - open one compartment, let fluid out, repair with skin graft

61
Q

What is muscle tone?

A

The tension in the muscle at rest

62
Q

What is muscle strength?

A

The muscles ability to contract and create force is response to resistance

63
Q

What is Duchene muscular Dystrophy?

A

An X linked recessive gene that causes a mutation in the dystrophin gene

64
Q

What occurs in Duchene Muscular Dystrophy?

A
Excess calcium enters the cell
Calcium taken up by mitochondria
Water taken in with calcium
Mitochondria burst
Muscle cell bursts (Rhabdomyolysis)
Muscle cell replaced with adipose
65
Q

What in the blood indicated Rhabdomyolysis has occurred?

A

`Extremely high levels of:

  • creatine kinase
  • myoglobin
66
Q

What markers are used to diagnose Cardiac Ischaemia?

A

Troponin I and T